A conventional system for human body communication, in which devices mounted on or placed near a human body communicate with one another through the human body as a communication medium, allows a communication channel to be formed when in contact with the human body. However, it is uncertain when a device embedded with a human body communication module will come in contact with the human body, and thus a signal needs to be periodically checked so as to find out whether a communication channel has been formed between corresponding devices. In this case, even if there is no contact with the human body, the device itself cannot recognize whether there is contact with the human body. Therefore, not only a receiving-end circuit that converts a weak signal received through the human body into a digital signal that can be processed by a micro-controller but also a micro-controller that performs a control operation has to be constantly or periodically in a wake-up state to reduce power consumption.
When a transmitter has data to be sent, even if a human body communication micro-controller initially operates after data is output to an external control signal or a designated memory area, a transmitter circuit that converts the digital signal received from the micro-controller into a signal to be output to the human body has to be operated in a normal state until contact with the human body has been made. That is, in order to check whether a channel is formed, the transmitter circuit has to operate even if there is no contact with the human body, which leads to unnecessary power consumption.
As described above, power is unnecessarily consumed because a transmitter/receiver circuit and a micro-controller for controlling the transmitter/receiver circuit have to constantly or periodically be in the normal state so as to determine whether a channel has been formed in transmitting and receiving processes even if there is no contact with the human body.